Air Flow Research - 1979-1995 Mustang - SBF 185cc Aluminum Street Heads AFR small block Ford 185 cylinder heads 185cc Street Heads, 68cc, Stud Mount, part number 1420. 185cc Street Heads, 68cc, Stud Mount. If you need the world’s finest street/strip small block Ford head, check out AFR’s all new 185cc intake port emissions legal aluminum cylinder heads. With lightweight 8mm 2.020 intake valves, 1.600” exhaust valves, combustion chamber volumes of 58cc or 72cc, and 68cc exhaust ports.